Tautomeric equilibrium in trifluoroacetaldehyde arylhydrazones

A series of p-substituted phenylhydrazones of trifluoroacetaldehyde (1) was synthesized and the azo-hydrazo (1–2) tautomeric equilibrium was investigated experimentally using correlation analysis and computationally with DFT methods. Investigation revealed strong impact of the substituent and solvent polarity on the tautomeric ratio (1/2). Calculations also revealed that acidity of the azo tautomers is similar to that of malonate esters.

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